1. Field of the Invention
The present invention relates to a mining tool for the breaking-down of minerals, particularly coal. The mining tool includes a chisel with a chisel shaft and a chisel holder with a shaft receiving means adjusted in shape to the chisel shaft. The chisel holder has an insertion bore and the chisel shaft has a receiving bore with a chuck for a locking or securing bolt. The insertion bore and the receiving bore extend essentially transversely of the chisel holder and the chisel shaft and are in alignment when the locking bolt is driven into the bores.
2. Description of the Related Art
In a known mining tool, the chisel shaft is fastened in the chisel holder by means of a securing wedge which is rectangular in cross-section. The chisel holder and the chisel shaft each have corresponding rectangular receiving means for driving in the securing wedge. The receiving means in the chisel holder additionally includes a jaw-like chuck. The securing wedge has sawtooth-like wedge surfaces which dig into the chuck in a manner of barbs in order to ensure a good fastening of the chisel shaft in the chisel holder.
In the above-described known mining tool, loosening of the fastening of the chisel is extremely problematic when the chisel must be replaced after it is worn or damaged or must be removed from the chisel holder for repair purposes. For removing the chisel, the rectangular securing wedge must be driven out of the receiving means together with the chuck against the clamping action created by the barb-like wedge surfaces when the wedge is driven in. The procedure is very complicated and time-consuming.
It is, therefore, the primary object of the present invention to provide a mining tool for the breaking-down of minerals, particularly of coal, of the above-described type in which the chisel cannot only be easily and quickly fastened in the chisel holder, but can also be easily and quickly separated, so that a quick exchange of chisels is possible.